Coexistence of hairy-cell leukemia and histiocytic lymphoma

A 69-year old man initially presented with hairy-cell leukemia (HCL), as evidenced by splenomegaly and the presence of abnormal mononuclear cells with irregular cytoplasmic borders in the peripheral smear. A year later, pathologic examination after diagnostic splenectomy and lymph node biopsy showed histiocytic lymphoma. Cell surface marker studies suggested B-cell proliferation. Bone marrow biopsy and electron microscopy were compatible with the presence of hairy cells, but the mononuclear cells were negative for tartrate resistant acid phosphatase staining. Chemotherapeutic treatment of the lymphoma was followed by leukopenia and then death. The occurrence of two B-cell disorders in one patient leads to speculation whether the two entities simply have similar characteristics or are part of a spectrum of a single disorder.